Qualitative Morphological Characterisation and Assessment of Genetic Diversity among Indigenous Landraces of Rice (Oryza sativa L.)

Key findings

• ▸Leaf collar and ligule presence were completely monomorphic across all 254 accessions (100% present, SWDI = 0.00), while panicle length of the longest awn recorded the highest diversity index of any trait studied (SWDI = 1.55), followed by awn colour (1.43), spikelet colour of the lemma tip (1.41), and lemma-and-palea colour (1.40).
• ▸Panicle branch attitude was highly variable (SWDI = 1.28), with semi-erect (40.94%), erect (30.70%), and erect-to-semi-erect (17.32%) types predominating among the 250 farmer-maintained landraces and four check varieties evaluated at JNKVV, Jabalpur during kharif 2024.
• ▸Flag-leaf attitude diversity roughly doubled between growth stages — from moderate at the early observation (SWDI = 0.89, erect 51.96%) to high by the late observation (SWDI = 1.32, adding horizontal 16.92% and deflexed 12.59% classes) — showing that the timing of DUS scoring changes how much variation gets captured.
• ▸Panicle curvature of the main axis (SWDI = 1.22) and panicle exertion (SWDI = 1.03) also showed considerable diversity, alongside pigmentation traits such as stigma colour (SWDI = 0.92) and lemma-keel anthocyanin colouration (SWDI = 0.92), confirming panicle architecture and pigmentation as the primary axes of variation in this indigenous rice germplasm collection.

Abstract

The present study evaluated morphological diversity among 254 rice accessions, comprising 250 indigenous landraces and four checks (IR 64, JR 206, Improved Jeerashankar, and Improved Chinnor), using qualitative DUS descriptors and the Shannon-Weaver Diversity Index (SWDI). The study aimed to identify variable traits that could support varietal documentation, germplasm characterisation, and use in rice breeding programmes. The accessions showed substantial variation in several reproductive, panicle, awn, pigmentation, and grain-related traits, whereas some vegetative traits were conserved. Leaf collar and ligule presence were monomorphic, with 100% occurrence and no diversity (SWDI = 0.00). Leaf auricle and anthocyanin pigmentation of the nodes and internodes also showed limited variation. The highest diversity was recorded for panicle length of the longest awn (SWDI = 1.55), followed by awn colour (SWDI = 1.43), spikelet colour of the lemma tip (SWDI = 1.41), lemma and palea colour (SWDI = 1.40), and flag-leaf attitude at late observation (SWDI = 1.32). Panicle branch attitude was also variable, with semi-erect (40.94%), erect (30.70%), and erect-to-semi-erect (17.32%) types predominating. Moderate diversity was observed for culm attitude, spikelet pubescence, stigma colour, panicle exertion, sterile lemma colour, and secondary branching intensity. Overall, SWDI values ranged from 0.00 to 1.55. The highly variable qualitative descriptors identified in this study may support genotype identification, DUS characterisation, germplasm conservation, and the selection of diverse parental material for rice improvement programmes.

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